Stable methylchloroform compositions



United States Patent O M 3,1131% STABLE METHYLCHLOROFOPM COMPOSITEONSPercy W. Trotter, Baton Rouge, La, assignor to Ethyl Corporation, NewYork, N.Y., a corporation of Virginia No Drawing. Filed May 27, 1960,er. No. 32,104 13 Claims. (Cl. 2.6i3652.5)

This invention relates to the degreasing of metals. In particular, itrelates to stable solvent compositions composed of 1,1,1-trichloroethanecontaining mixtures of stabilizing additives which prevent metal induceddecomposition.

The problem of stabilizing chlorinated aliphatic hydrocarbons-viz,carbon tetrachloride, trichloroethylene, tetrachloroethylene, ethylenedichloride, etc., useful as solvents for degrcasing metals has receivedconsiderable attention by skillful chemists over many years. It has,however, become increasingly apparent that the discoveries relative tothe stabilization of particular chlorinated hydrocarbon solvents areneither applicable nor translatable to the problems of stabilizing otherchlorinated hydrocarbon solvents. Even where a successful stabilizingadditive has been found for a particular chlorinated hydrocarbonsolvent, the stabilized composition still may not meet the rigorousrequirements of commercial applications.

Some stabilizing additives thus provide some degree of protectionagainst decomposition of the chlorinated hydrocarbon solvents or againstattack upon the metals themselves in liquid and vapor phase but yet donot provide sufficient protection for commercial use. A commerciallyacceptable stabilizing additive, for example, must also be capable ofinhibiting against metal induced decomposition of the chlorinatedhydrocarbon solvent under hydrolytic conditions. Often a stabilizer,otherwise acceptable commerically, fails to meet this stringentrequirement and when a very small amount of water is introduced into thsystem severe corrosion of the metal and decomposition of the solventresults. Also, a stabilizing additive other wise acceptable, is oftenrejected by the trade because it adds color to the chlorinatedhydrocarbon solvent. Cost of the stabilizing additive is another factorwhich can influence the commercial acceptance of stabilizers.

Insofar as stabilizing 1,1,l-trichloroethane (methylchloroform) isconcerned, the problems are even more acute. From the standpoint ofmetal induced decomposition, 1,1,l-trichloroethane departs drasticallyfrom the norm of other chlorinated hydrocarbons. For example, metals,especially aluminum, will last for days or weeks without being attackedby ordinary chlorinated hydrocarbon solvents, but in the presence ofl,l,l-trichloroethane, however, aluminum is virgorously attacked and the1,1,1- trichloroethane solvent reduced to a blackened or charred massWithin minutes. Only a few stabilizers are known which are reasonablyeffective in inhibiting 1,1,l-trichloroethane against such attack andwhy these few stabilizers are effective is not known. The mere facthowever that a stabilizer will inhibit decomposition of otherchlorinated hydrocarbons means absolutely nothing in relation tostabilizing 1,1,1-trichloroethane.

The problem of stabilizing 1,1,l-trichloroethane in the vapor phase isespecially actuate because even a stabilizer which is useful forstabilization in the liquid phase is useless for stabilizing the vaporphase unless it has sufli- B d. Hi 54 Patented Dec. 3, 1963 cientvolatility to stabilize the vapor phase, and yet it cannot have suchvolatility as to unduly deplete the liquid phase. No commercial vaporphase stabilizer for 1,1,1- trichloroethane is yet known.

It is accordingly an object of this invention to provide stabilizedcompositions which are highly effective for degreasing aluminum, ironand other metals. A particular object is to provide1,1,1-trichloroethane solvent compositions which retain chemicalpassivity during repeated cycles of exposure to metals at processingconditions, and against the degradation influences of moisture, elevatedtemperature, contact with metals and metal halides, and light. Anotherobject of the present invention is to provide compositions especiallysuitable for the vapor phase degreasing of aluminum and other metals. Afurther object is to provide additive compositions especially adaptedfor use in methyl chloroform as stabilizers therefor.

These and other objects are achieved according to the present inventionwhich comprises forming a stable 1,1,1- trichloroethane solventcomposition by dissolving within 1,l,l-trichloroethane a novel mixtureof additives in a quantity suflicient to inhibit against decomposition.The stabilizing mixture is one consisting essentially of a dioxolane, amono-olefin and an amine compound. On the basis of outstandingeffectiveness and low cost, the preferred class of stabilizing additivesare those wherein the dioxolane compound is a 1,3-dioxolane containingup to two alkyl substituents each having from 1 to 2 carbon atoms, themono-olefin is an alkene hydrocarbon having from about 6 to about 8carbon atoms and the amine is a compound selected from a groupconsisting of alkyl amines containing from about 4 to about 6 carbonatoms, morpholine and pyridine.

In an especially preferred embodiment of this invention the stabilizingmixtures of dioxolane, mono-olefin and amine compounds, added to thel,l,-1-trichloroethane, are preferably 1,3-dioxoiane compoundscontaining up to one alkyl substituent having from 1 to 2 carbon atoms,a mono-olefin which is an alkene hydrocarbon having from about 6 toabout 8 carbon atoms and an alkyl amine containing from about 4 to about6 carbon atoms. These systems have superb stabilizing proper-ties,particularly against iron even under hydrolytic conditions, and even inthe stabilization of 1,1,1-trichloroethane in the vapor phase.

An even more highly preferred embodiment in one wherein the stabilizingmixture for 1,1,l-trichloroethane consists essentially of 1,3-dioxolane,diisobutylene, and n-butyl amine. This particular combination ofadditives shows outstanding stabilizing properties and in the presenceof iron does not discolor or cause corrosion of the iron even undersevere hydrolytic conditions. In short, on a cost-etfectiveness basisthis ternary system is particularly outstanding.

In yet another especially preferred embodiment of this invention, thedioxolane, mono-olefin and the amine compounds are blended together toform additive concentrates or corrosion inhibitor compositions. Thesecompositions form homogenous and essentially colorless solutions whichcan be added rapidly and conveniently to 1,1,1-trichloroethane in alldesired proportions. The inhibited 1,1,l-trichloroethane compositionsthus formed are highly resistant both to decomposition of the solventand to corrosion of the metal with which the solvents are placed incontact. In particular, these additive concentrates when blended with1,1,l-trichloroethane form highly useful compositions for degreasing thesurfaces of metals. Accordingly, another preferred embodiment of thisinvention is that of degreasing metal by contacting the surfaces ofmetal with 1,1,l-trichloroethane while maintaining a stabilizing mixtureof a dioxolane, a mono-olefin and an amine dissolved within the1,1,1-tric'hloroethane in sufficient quantity to inhibit the1,1,l-trichloroethane against decomposition.

in accordance with the practice of this invention, 1,1,1-trichloroethane is provided with an additive concentrate composed of amixture of from about percent to about 75 percent of a dioxolanecompound, from about to about 85 percent of a mono-olefin compound andfrom about 0.1 to about 10 percent of an amine compound, based on thetotal weight of the additive concentrate or corrosion inhibitorcomposition. A particularly preferred inhibitor composition is onecomposed of about to weight percent of a dioxolane compound, from about55 to 65 weight percent of a mono-olefin compound and from about 1 to 3weight percent of an amine compound because it provides very highstabilizing benefits under general commercial degreasing conditions.This composition is also available at low cost.

A small amount of this stabilizing mixture, in a quantity suflicient toinhibit the 1,1,1-trichloroethane against decomposition, is added to the1,1,1-trichloroethane. Generally a minor amount of this stabilizingmixture, suitably about 0.3 to about 15 weight percent (based on theweight of the total inhibited solvent), added to the 1,1,1-trichloroethane solvent forms a highly effective system which resistsdeteriorating influences such as contact with aluminumeven freshlyexposed aluminum surfacescopper, zinc and other metals, exposure tolight and subjection to elevated temperatures. These mixtures areparticularly effective in preventing attack upon iron metal, or alloysof iron, which are especially susceptible to attack under hydrolyticconditions. The stabilizing mixtures also form clear and almostcolorless solutions which are accepted without preiudice by the trade.This attitude is in sharp contrast to many other situations wherestabilizing mixtures are rejected on the basis that they add color tothe solvent. A preferred concentration of any of these stabilizingmixtures in 1,1,l-trichloroethane is from about 4 to about 10 weightpercent because of the excellent properties of the resulting compositionto resist deterioration. A 6 percent concentration is especiallypreferred because of the excellent properties of the resultingcomposition to resist deterioration under commercial openatingconditions. It will be understood however that the concentrations of thepresent stabilizers can be varied beyond the ranges given above withoutloss of most of the benefits of this invention and without departingfrom the scope of this invention.

It was heretofore discovered by one of my colleagues that thesedioxolane compounds when used alone are highly effective stabilizers for1,1,1-triohloroethane. It has now been discovered that the inhibitingpowers of these dioxolane compounds can be even further enhanced by theuse of particular mono-olefin and amine compounds. This in indeedunexpected for the latter compounds in themselves, alone or admixed, arepoor stabilizers for 1,1,l-trichloroethane. Thus, while the discovery ofthese dioxolane compounds as inhibitors for 1,1,1- trichloroethane hasbeen of great importance and of significance,dioxolane-1,1,1-trichloroethane systems nevertheless do have oneshortcoming. The dioxolane-1,1,1- trichloroethane compositions do leavesomething to be desired when hydrolytic conditions occur and thesecompositions are in contact with iron, particularly with certain formsof iron and under extended hydrolytic conditions. The iron, underhydrolytic conditions, does undergo significant corrosion. The corrosionof iron under hydrolytic conditions is considerably and significantlyreduced i by use pursuant to this invention of a dioxolane, monoolefinand an amine compound in the 1,1,l-trichloroethane solvent. Inparticular, the value of dioxolane as a vapor phase inhibitor is greatlyenhanced by the addition thereto of a mono-olefin and an amine compound.

This invention then is based on the discovery that the value andeffectiveness of these dioxol'anes as stabilizers, particularly as vaporphase stabilizers, for 1,1,l-trichloroethane can be even furtherenhanced by the addition thereto of specified mono-olefin and aminecompounds. in particular, these stabilizing mixtures considerablyenhance the ability of the 1,1,1-trichloroethane to resist deteriorationin the presence of iron metal and its alloys. This is true even undersevere hydrolytic conditions.

Thus, additive concentrates or inhibitor compositions made up ofmixtures of idioxolanes and specified monoolefin and amine compounds canbe formed and added to 1,1,l-trichloroethane and outstanding resultsachieved. As stated, this is especially true where the stabilized 1,1,1-trichloroethane-dioxolane compositions are used in contact with iron andunder hydrolytic conditions. However, the several additive ingredientsof the stabilizers of this invention can be blended with the1,1,Ltrichloroethane either individually or in various subcombinations.

The following representative experimental data provide a sound basis fora clear appreciation of this invention. In the demonstration immediatelyfollowing a stabilized composition of1,3-dioxolane-l,1,1-trichloroethane is employed with iron underdegreasing conditions. Accordingly, to parts by weight of methylchloroform contained within a reaction vessel were added 3 parts byweight of 1,3-dioxolane. Above the reaction vessel were suspended 2tared strips of soft iron. The mixture was then continuously refluxedfor 67 hours, the vapors condensing upon the strips of iron and pouringback into the vessel. After this time the tared metal strips were dried,cleaned and reweighed. The average weight loss of the two iron stripswas 0.14 percent by weight.

To show the benefits derived from the practice of this invention whereina mono-olefin and an amine compound are used in combination withdioxolane, a mixture of dioxolane and the former compounds was added to1,1,1- trichloroethane, and a demonstration performed under even morerigorous conditions as in the following ex ample.

EXAMPLE I To 100 parts by weight of methyl chloroform was added astabilizing mixture consisting of 2.9 parts by weight 1,3-dioxolane, 5parts by weight diisobutylene and 0.2 part by weight n-butylamine. Next,four tared strips of iron were suspended above the reaction vesselcontaining the stabilized solvent. The temperature of the mixture wasthen raised to boiling and reflux continued for 96 hours. After thattime the iron strips were removed from the vicinity of the reactor andexamined. The iron appeared completely unaffected and its surfaceremained bright and clear. The 1,1,1-trichloroethane solvent showed onlyslight evidence of any discoloration. The average weight loss of thefour iron strips was less than 0.02 percent.

EXAMPLE II The foregoing example was repeated in all deails except inthis instance four aluminum metal strips were substituted for the ironmetal. After refluxing again for 96 hours the four aluminum strips wereremoved, dried and reweighed. The average weight loss of the fouraluminum strips was only 0.015 percent.

The following Table I shows other three-component systems of highlypreferred additive concentrates consisting of dioxolane, mono-olefin andamine compounds. These systems of additive concentrates correspond inrelative concentrations of components to each other as that of thestabilizing mixture employed in Example I.

Table I Example Dioxolane Mono-Olefin Amine Compound Compound Compound1,3-dioxo1ane IIexene-l Triethylamine.

do 2,3dimethylbutene-1- diisopropylamine. V do 2,4,4-trimethy1 pen-Di-n-propyltenel. amine. VI do 2,4l-dimethylpentene- Hexylamine.

EXAMPLES III-VI The systems of additive concentrates, II-VI,respectively, are added to 1,1,1-trichloroethane solvent in sufiicientquantity to form .03, .05, 1, 2, 4, 5, 6, 10, 12 and 15 percentcompositions, respectively. The procedure of Example I is again repeatedwith each of these compositions. At the termination of each of the runsthe 1,1,1- trichloroethane solvent remains essentially colorless andthere is no visible evidence of any corrosion.

In the following examples (VIIXVII), a wide variety of additiveconcentrates, varying with respect to the individual compounds employedand with respect to their relative proportions to each other, are formedas shown in Table II.

Table I I Example Dioxolane Mono-Olefin Amine Compound Compound CompoundVII percent 58 percent 5 percent tri- 5-1nethyl-1,3- heptene-l.ethylamine. dioxolane.

VIII 10 percent 80 percent 10 percent 4-methyl-1,3- 2,3-dimethy1n-butylamine. dioxolane. butene-l.

IX 20 percent 72 percent 8 percent 2-methy1-1,3- 2,3-dimethyltriethylamine. dioxolone. butene-2.

X 30 percent 64 percent 6 percent 2-ethy1-1.3- Z-methyldiisopropyldioxolanc. pcntcne-2(cis). amine.

XI. 40 percent 56 percent 4 percent 4-mcthyl-1,3- 2-1nethyldi-n-propyldioxolane. pentene-2 amine.

(trans).

XII. 50 percent 47 percent 3 percent 4-ethyl-1,3- 2,4, i-trimethylethyl-n dioxolane. pentene-1 butylamine.

XIII. 60 percent 38 percent 2 percent 5-methyl-1,3- 2,3,3-trimethylmethyl-n dioxolane. pentene-l. butylamine.

XIV 65 percent 34 percent 1 percent methyl 5ethyl-1,3- 2,4-dimethylethyl propyl' dioxolane. pentene-Z. amine.

XV 70 percent 29.5 percent 0.5 percent methyl 1,3-dioxolane. heptene-l.ethyl isopr0pyl amine.

XVI 75 percent 24.9 percent 0.1 percent methyl 1,3dioxolane.2,3,3-trimethy1 ethyl-n-propylbutene-l. amine.

XVII-.." 70 percent 20 percent 10 percent 1,3-dioxo1ane. 2,3,3-trimethylmethyl ethylbutcne-l. n-propylamine.

The stabilizing mixtures, or corrosion inhibitor compositions, shown inExamples VII through XVII are added to 1,1,1-trichloroethane to formstabilized 1,1,l-trichloroethane compositions. The corrosion inhibitorcompositions are added to the 1,1,l-trich1oroethane in sufficientquantity to form 0.3, 0.5, 1, 2, 4, 5, 6, 10, 12 and 15 weight percentcompositions of the stabilizing mixtures in 1,1,1-1trichloroethane.

Example I is repeated with each of these stabilized1,1,l-trichloroethane compositions. As in Example I, the solvents showlittle or no signs of decomposition. The metals also show little or nosigns of chemical attack.

When Examples I and II are repeated with each of the compositions ofExamples VII through XVII except that the metals are completely immersedwithin the stabilized 1,1,1-trichloroethane solvent, similar results areobtained.

The corrosion inhibitor compositions of Examples XVIII through XXVI(Table III) are added to 1,1,1-trichloroethane in sufficient quantity ofform 0.3, 0.5, 1, 2, 4, 5, 6, 10, 12 and 15 weight percent compositionsof the stabilizing mixtures in 1,1,1-trichl0roethane. Examples I and IIare then again repeated with each of these compositions. As in ExamplesI and II the solvent compositions show little or no signs ofdecomposition and the metals are essentially unattacked.

Table 111 Example Dioxolane Mono-Olefin Amine Compound Compound CompoundXVIII 10 percent 85 percent 5 percent ethyl 2,2 diethy1-L3- l-hcxenc.propylamine. dioxolane.

XIX. 20 percent 76 percent 3-ethyl 4 percent ethyl l-methyLZ- butane-1.methyl propylethy1 1,3- amine. dioxolane.

XX 30 percent 67 percent 4-ethyl 3 percent 2,2-dirnethylpentene-l.dimethylbutyl- 1,3-dioxolane. amine.

XXL percent 2,4- 58 percent 2 percent dietl1yl-1,3- 5-ethylhexcne-1.n-butylamine. dioxolane.

XXIL percent 4,4- 49 percent 1 percent ethyl dimetl1yll,3- Z-methylbutylamine. dioxolane. pentene-2.

XXIII. percent 39.5 percent 0.5 percent ethyl 2-methyl-5- Z-ethylmethylbutylethyl-1,3- butene-Z. amine. dioxolane.

XXIV percent 34.5 percent 2,4,4- 0.3 percent 2-methyl-5-trimethylethylamine. ethyl-1,3- pentene-l. dioxolane.

XXV percent 5,5- 23 percent '7 percent diethy1-1,3- hexane-1.n-butylamine. dioxolane.

XXVL.-. percent 4,5- 20 percent 2,3,3- 5 percent diethyl-LS-trimethyln-butylamme. dioxolane. butene-l XXVII 70 percent 4,5- do 10percent diethyl-1,3- n-butylaminc. dioxolane.

EXAMPLES XXVIII-XXIX Examples XVIII through XXVII are repeatedsubstituting morpholine and pyridine, respectively, for the amine ineach of the examples. Again highly satisfactory corrosion inhibitorcompositions are produced for stabilizing 1,1 l-trichloroethane.

In the practice of this invention, a minor concentration of the mixtureof components or additive concentrates is added to the1,1,1-trichloroethane. Any concentration of these compounds will producesome stabilizing eiIect, and the quantity of the stabilizing mixture tobe added is therefore largely contingent upon the use of which thestabilized solvent will be employed. Generally, however, stablecompositions consisting essentially of from about 0.3 to about 15 weightpercent of the mixture of additives in 1,1,1-trichloroethane are formed.These compositions form highly effective systems which resist thedeteriorating influences such as contact with aluminum, iron and othermetals, salts of such metals, light, water and elevated temperatures. Apreferred concentration of the stabilizing mixture in1,1,1-trichloroethane is from about 4 to 10 weight percent.

As was stated, a wide variety of dioxolane, mono-olefin and aminecompounds are suitable for the practice of this invention.

Nonlimiting examples of the highly preferred dioxolane compoundssuitable in the practice of this invention include 1,3-dioxoiane,2-methyl-1,3-dioxolane, 4-methyl- 1,3 dioxolane, 5 methyl 1,3 dioxolane,2-ethyl-1,3-dioxolane, 4-ethyl-1,3-dioxolane, 5-ethyl-1,3-dioxolane, andin general those compounds boiling within a range of from about 50 C. toabout 120 C., preferably from about 65 C. to about C., and the like.Other preferred dioxolane compounds include 2,2-dimethyl-1,3- dioxolane,4,4-dimethyl-1,3-dioxolane, 5,5-dimethyl-1,3-dioxolane,2,4-dirnethyl-1,3-dioxolane, 2,5-dimethy1-1,3-di oxolane,2,2-diethyl-1,3-dioxolane, 4,4-diethyl-1,3-dioxolane,5,5-diethyl-1,3-dioxolane, 2,4-diethyl-1,3-dioxolane,2,5-diethyl-1,3-dioxolane, Z-methyl-Z-ethyl-1,3-di0xolane,2-methyl-4-ethyl-1,B-dioxolane, 2-rnethyl-5-ethyl-1,3dioxolane,2-ethyl-4-rnethyl-1,3-dioxolane, Z-ethyl-S-methyl- 1,3-dioxolane, andthe like.

Nonlimiting examples of mono-olefins of this invention include hexene-1,hexene-Z, hexene-3, 2,3-dimethyl butene-l, 2,4-dimethyl butene-l,3,4-dimethyl butene-l, 2,3-dimethyl butene-Z, 3-ethyl butene-l, 2-methylpentene- 1, Z-methyl pentene-Z, B-methyl pentene-2, heptene-l, 3- methylhexene-l, 3,3-dimethyl pentene-2, 3-methyl-3-ethyl butene-l, 3,3-diethylpropene-l, octene-l, octene-3, 2- methyl heptene-l, 2,3-dimethylhexene-l, 2,4-dimethyl hexene-l, 3-ethyl hexene-Z, 2-methyl-3-ethylpentene-l, 2- methyl-4-ethyl pentene-l, 3,3-diethyl butene-l,1,1,2-trimethyl butene-2, and in general those compounds boiling withina range of from about 50 C. to about 120 C., preferably from about 65 C.to about 85 C., and the like.

Nonlimiting examples of highly preferred amines are such alkyl amines asbutyl amine, diethyl amine, methyl propyl amine, methyl isopropyl amine,methyl butyl amine, ethyl isopropyl amine, ethyl n-propyl amine, methyldiethyl amine, dimethyl propyl amine, amyl amine, methyl amyl amine,ethyl n-butyl am ne, triethyl amine, methyl ethyl isopropyl amine,diisopropyl amine, di-n-propyl amine, methyl amyl amine, and in generalthose compounds boiling within a range of from about 50 C. to about 120(3., preferably from about 65 C. to about 85 C., and the like.

Other highly suitable amines include morpholine, pyridine, and the like.

Having described the invention, what is claimed is:

1. A stable solvent composition for the degreasing of metals,said'solvent consisting essentially of 1,1,1-trichloroethane withinwhich is dissolved from about 0.3 to about 15 weight percent of astabilizing mixture of additives consisting essentially of from about 10percent to about 75 weight percent dioxolane, from about 20 to about 85weight percent of mono-olefin and from about 0.1 to about 10 Weightpercent amine, to inhibit the 1,1,1- trichloroethane againstdecomposition, said dioxolane being 1,3-dioxolane characterized bycontaining in the molecule up to two alkyl substituents each having fromone to two carbon atoms, said mono-olefin being an alkene hydrocarboncharacterized by having from about 6 to about 8 carbon atoms in themolecule and said amines being selected from a group consisting ofmorpholine, pyridine and alkyl amines characterized by containing in themolecule from about 4 to about 6 carbon atoms.

2. The composition of claim 1 wherein the dioxolane is 1,3-dioxolane.

3. The composition of claim 1 wherein the mono-olefin is diisobutylene.

4. The composition of claim 1 wherein the amine is n-butyl amine.

5. The composition of: claim 1 wherein the dioxolane is 1,3-dioxolane,the mono-olefin is diisobutylene and the amine is n-butyl amine.

6. The composition of: claim wherein the stabilizing mixture ofadditives is present within the 1,1,1-trichloroethane at a concentrationof from about 4 to about 10 weight percent.

7. The composition of claim 5 wherein the stabilizing mixture ofadditives is present within the 1,1,1-trichloroethane at a concentrationof about 6 weight percent.

8. A 1,1,1-trichloroethane corrosion inhibitor composition composed of amixture of from about 10 percent to about 75 percent of dioxolane, fromabout percent to about 85 percent of an alkyl mono-olefin, and fromabout 0.1 to about 10 percent of an amine, based on the Weight of thecorrosion inhibitor composition, said dioxolane being 1,3-dioxolanecharacterized by containing up to two alkyl substituents each havingfrom one to two carbon atoms, said mono-olefin being an alkenehydrocarbon characteirzed by having from about 6 to about 8 carbonatoms, said amine being selected from a group consisting of morpholine,pyridine and alkyl amines characterized by containing in the moleculefrom about 4 to about 6 carbon atoms.

9. The composition of claim 1 wherein the stabilizing mixture ofadditives is present within the 1,1,1-trichloroethane at a concentrationof from about 4 to about 10 weight percent.

10. The composition of claim 1 wherein the stabilizing mixture ofadditives is present within the 1,1,1-trichloroethane at a concentrationof about 6 weight percent.

11. The composition of claim 1 wherein the stabilizing mixture dissolvedwithin the 1,1,1-trichloroethane consists essentially of from about toabout weight percent of dioxolane, from about to about weight percentmono-olefin and from about 1 to about 3 weight percent amine.

12. The composition of claim 11 wherein the concentration of thestabilizing mixture in 1,1,1-trichloroethane is from about 4 to about 10weight percent.

13. The composition of claim 11 wherein the concentration of thestabilizing mixture in 1,1,1-trichloroethane is about 6 weight percent.

References (Jited in the file of this patent UNITED STATES PATENTS1,904,450 Harris Apr. 18, 1933 2,094,367 Missbach Sept. 28, 19372,371,645 Altchison et a1. Mar. 20, 1945 2,517,894 Larcher Aug. 8, 1950

1. A STABLE SOLVENT COMPOSITION FOR THE DEGREASING OF METALS, SAIDSOLVENT CONSISTING ESSENTIALLY OF 1,1,1-TRICHLOROETHANE WITHIN WHICH ISDISSOVLED FROM ABOUT 0.3 TO ABOUT 15 WEIGHT PERCENT OF A STABILIZINGMIXTURE OF ADDITIVES CONSISTING ESSENTIALLY OF FROM ABOUT 10 PERCENT TOABOUT 75 WEIGHT PERCENT DIOXOLANE, FROM ABOUT 20 TO ABOUT 85 WEIGHTPERCENT OF MONO-OLEFIN AND FROM ABOUT 0.1 TO ABOUT 10 WEIGHT PERCENTAMINE, TO INHIBIT THE 1,1,1TRICHLOROETHANE AGAINST DECOMPOSITION, SAIDDIOXOLANE BEING 1,3-DIOXOLANE CHARACTERIZED BY CONTAINING IN THEMOLECULE UP TO TWO ALKYL SUBSTITUENTS EACH HAVING FROM ONE TO TWO CARBONATOMS, SAID MONO-OLEFIN BEING AN ALKENE HYDROCARBON CHARACTERIZED BYHAVING FRORM ABOUT 6 TO ABOUT 8 CARBON ATOMS IN THE MOLECULE AND SAIDAMINES BEING SELECTED FROM A GROUP CONSISTING OF MORPHOLINE, PYRIDINEAND ALKYL AMINES CHARACTERIZED BY CONTAINING IN THE MOLECULE FROM ABOUT4 TO ABOUT 6 CARBON ATOMS.